Effect of Nickel and Cobalt Doping on Nano Bismuth Ferrite Prepared by the Chemical Route

Abstract

Bismuth ferrite is an important multiferroic single-phase material with a distorted perovskite structure with Tc = 1100 K (Curie temperature), Tn = 640 K (Neel temperature) coupled with ferroelectric properties and spin-cycloid ferromagnetic properties. Undoped as well as doped bismuth ferrites are prepared from precursor salts via a chemical route and then calcinated at 300°C and sintered at 500°C for a fixed time interval of 30 min. Phase purity of the synthesized samples is investigated with an X-ray diffractometer. Crystallite sizes, calculated using Scherrer’s relation, are found to be in a range between 15 and 50 nm for both undoped and doped samples. FESEM images of the synthesized material reveal a microstructural morphology.

An agglomeration tendency in certain regions with polyhedral morphology is observed. EDX analysis confirmed Co and Ni doping in the bismuth ferrite. Optical properties, mainly band gap of undoped, Ni- and Co-doped BFO are examined with UV-VIS spectra using the Tauc relation. A P-E loop is obtained for both undoped and transitional-metal-doped BFO samples. The characteristics of the P-E loop shows different behaviors for the undoped and doped BFO samples confirming both the doping and its effect on the system. Dielectric measurements are also carried out for both undoped and transitional-metal-doped BFO samples.